遺失|いしつishitsu[0]heiban (flat)

1. noun, suru verb, transitive verbloss

• Synonym紛失ふんしつNeutralThe everyday and notice-board word for something going missing; 「遺失」 itself now survives mostly in legal terms like 「遺失物」.
• Synonym失ううしなうNeutralBroad verb for losing, covering loved ones, opportunities and other abstract things as well as objects.
• SynonymなくすNeutralThe most common everyday verb for losing things; also means to eliminate or get rid of, as in 「無駄をなくす」.
• Synonym亡失ぼうしつWrittenWritten word for losing property; very rare even in prose — say 「紛失」 instead.
• Related喪失そうしつNeutralLosing something, used mostly for abstract things such as rights, confidence or memory, as in 「記憶喪失」.
• Related落とすおとすNeutralEveryday verb for dropping or losing something; the most common choice in speech. Also covers lowering, removing and other senses.
• Related置き忘れるおきわすれるNeutralLeaving something somewhere and forgetting to take it with you; the point is where you left it, not the loss itself.
• Related見失うみうしなうNeutralLosing sight of a target — usually a person or a direction — and not knowing where it went; not for misplaced objects.
• Related忘れるわすれるNeutralTo forget; also forgetting to bring something, as in 「傘を忘れる」. The focus is on memory, not the object's whereabouts.
• Related取り落とすとりおとすNeutralDropping something you were holding because you failed to keep your grip on it; the nuance is fumbling, not misplacing.
• Related忘失ぼうしつWrittenWritten word for losing something through forgetting; very rare — in daily speech use 「忘れる」 or 「なくす」.
• Related落っことすおっことすCasualColloquial form of 「落とす」 for accidentally dropping something; carries a casual, informal tone.
• Related無くなすなくなすCasualA colloquial or dialectal variant of 「なくす」 meaning to lose something; heard less often.
• Related置き違えるおきちがえるNeutralPutting something in the wrong place; the problem is the mistaken location, not that the item is lost.
• Antonym発見はっけんNeutralAntonym: finding or discovering something unknown or lost; the counterpart to something going missing.
• Antonym拾得しゅうとくWrittenAntonym: picking up lost property that belongs to someone else; a legal term that pairs with 「遺失」.

In everyday speech say 「なくす」 or 「落とす」; for notices and official procedures use 「紛失」. 「遺失」 itself now appears mainly in legal language such as 「遺失物」, while 「喪失」 is the word for losing abstract things. The other verbs above cover specific situations — dropping, leaving behind, forgetting — and 「発見」 and 「拾得」 are the opposites.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 金品きんぴんを失なくしたり、置おき忘わすれたりすること。